| From Wikipedia, the free encyclopediaThallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal is not found free in nature. When isolated, it resembles tin, but discolors when exposed to air. | |||||||
Thallium in the periodic table | |||||||
|---|---|---|---|---|---|---|---|
| Symbol | Tl | ||||||
| Atomic number | 81 | ||||||
| Group | 13 | ||||||
| Period | 6 | ||||||
| Block | p | ||||||
| Element category | Post-Transition Metal | ||||||
Physical properties | |||||||
| Phase at STP | Solid | ||||||
| Density | 11.85 g/cm3 | ||||||
| Atomic weight | 204.38 u | ||||||
| Melting point | 577 K 303.85 °C 578.93 °F | ||||||
| Boiling point | 1746 K 1472.85 °C 2683.13 °F | ||||||
Atomära egenskaper | |||||||
| Electronegativity (Pauling Scale) | 1.62 | ||||||
| Electron affinity | 36.4 kJ/mol | ||||||
| Ionization energies |
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Electron configuration | |||||||
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p1 | ||||||
| Electrons per shell | 2, 8, 18, 32, 18, 3 | ||||||
History | |||||||
| Discovered | 1861 | ||||||
| Discovered by | William Crookes | ||||||